The invention generally concerns a process for removing phthalide from a composition that includes diisooctyl phthalate and phthalide. In particular aspects, the phthalide can be removed by contacting the composition with activated carbon or a silica containing material such as silica gel or diatomaceous earth, or any combination thereof.
Diisooctyl phthalate (DOP), also referred to as di-2-ethylhexyl phthalate (DEHP), is a commonly used plasticizer from the phthalate ester family and has been in use in flexible polyvinyl chloride (PVC) products for at least 60 years. These flexible PVC products are used in a wide range of applications and materials found in buildings, automotive parts, medical devices or equipment, and packaging applications.
Plastics used in medical devices are oftentimes sterilized with ultraviolet (UV) radiation (wavelength of about 100 to 400 nm). Such radiation can degrade the plastic and ultimately lead to plastic failure. This can be exacerbated if the plastic is efficient at absorbing UV radiation, as such absorption can result in the loss of the physical and chemical properties of the plastic. The international standard ISO 3826-1:2003 for Plastics Collapsible Containers for Human Blood and Blood Components states that the maximum permissible absorbance value of a plastic container having a capacity of less than 100 ml is 0.25 in the range of 230 nm to 360 nm. For containers greater than 100 ml, the maximum absorbance value is 0.2 for the same wavelength range. The current options available for meeting these standards are to use ingredients in the plastic that either have low absorption properties within the 230 nm to 360 nm range or to limit the amount of ingredients that may absorb within this range.
While DOP is a well-known plasticizer, the currently available commercial sources of DOP fail to meet international standards relating to the absorption properties of this plasticizer for use in medical equipment and medical devices. Further, the vast majority of processes known to purify DOP are not even concerned with UV absorption—rather, such processes relate to decolorizing DOP so that it can be optically clear and not affect the color of the resulting plastic product.